Process of cleansing wells and apparatus therein



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atenteel Jane l7, lldZd.

barre earns WEQANCIQ W. with, @JF FULLERTUN, AND BERT W. PEPE, 01? B CAMEQ J.

To all whom it may concern:

Be it kno that we, FRANCIS W. LAKE and ROBERT W. Piunnre, citizens of the United States, residing, respectively, at Fullerton and Brea, in the county of Orange and State of Galifornia, have jointly invented a new and useful Process of Cleansing Wells and Apparatus Therein, of which the following is a specification.

This invention relates to a process of cleansing wells and apparatus therein. The invention has for an object the provision of a novel process which readily removes colloidal muds, clays, et cetera, from the walls of the well hole or from any apparatus or members within said well hole, and which muds would tend to clog or otherwise obstruct the flow of oil or gas through such apparatus or well hole. The invention contemplates destruction of the colloidal properties of the muds, clays, etc.

A further object is the provision of a novelprocess which ,is easy to use and performs its work in an efficient manner and,

quickly. y

In practicing the invention, and assuming that a well hole is being bored by the rotary system, it is apparent that as the rotary tube moves downwardly. any sand formations that might contain oil are plastered by the colloidal muds during the boring operation. Various means have been used such as the s raying of water under pressure against the wall of the well hole after said hole has been bored in an attempt to remove the colloidal muds and allow the oil, if any, to'percolate throughthe sands and into the well It often happens that valuable oil sands are completely lost when the rotary system is used, by the walls of the well hole being so plastered as to prevent any oil from seeping into the well hole. Our invention contemplates a process which will clean the well hole of all the colloidal muds, and allow the oil and gas to enter the well hole so that it may be recovered. A clean well hole is to be desired before cementing operation is carried on, and the present process will cleanse the walls of the wall for such cementing without in any manner attacking the cement.

In accordance with the invention we introduce a suitable acid, such as commercial nitric acid, hydrochloric or sulphuric acid, or in fact, most any form of acid or mixtures thereof, within the well hole, by passlhdp d @F (CLEANSING WELLS AND APPARATUS i i v 1923. Qerial N0. Wflbl).

is necessary for the acid or the solution thereof to stand for a certain time within the well hole in order to complete its action. As to the percentage of acid to water, or the normal strength of the acid, or the volume of mud, no fixed ratios have to be ob served, for the reason that the speed of elimination of the colloids is generally proportionate to the strength and volume of the acid used. It is, found that the mud colloids in the well hole are broken up entering partially into solution mechanically or chemically, and partially being subdivided into small compact masses by the acid solution, and that the acid solution seems to have a greater afinity for the colloidal mud than it has for the metallic casing through which said acid is introduced into the well hole. After the colloidal mud has been broken up by the acid solution so that the mud becomes freely suspended or dissolved in the water, it may then be removed from the hole by mechanical action of the water acting as a vehicle for transporting it. As has been pointed out, water alone will not produce sufficient mechanical action to break down the colloidal mud from the walls of the well hole and that the acid in the water, of any proper strength, breaks up and destroys the tenacious colloids in an eficient and rapid manner, which, as altered sands, clays, etc, may then be removed by the aqueous vehicle.

It is found that the acid or acids used for these purposes will not appreciably attack the metallic structures in the well hole, such as tubing and casing, collars, and the like, where mud is present in the hole, unlessused to excess, inasmuch as when an approte balance between the amount of acid and colloidal mud is maintained the acid action will .mud will be put into suspension in the fluid or the colloidal properties destroyed, or both.

andthe residue may be removed prior to any appreciable attack upon the metals by the acid.

The use of this process does not cause attack or injury of cement in the hole. whether it be set cement. or neat cement or cement being introduced in liquid form, nor does it interfere with the setting of such liquid cement, and if cement be present in the hole during the carrying on of the process the acid will act upon the 'cement. to produce a thin -superficial film or jelly which will protect the cement against further invasion by the acid: so that the process is not only highly etlicient for cleansing wells and removing therefrom adhering colloidal muds, clays. shales, or other earths, but the results are etiected without injury to the metal materials in the hole or cement masses, either liquid or neat cement present therein, and in the case of set cement. acts to produce a protective covering for the cement mass, thus ensuring the integrity of the cement against its own further action. So that the process is both etiicient and non-damaging to anything in the well hole.

The. process as herein described, so far as we are aware, is'broadly new and has never been accomphshed before to our knowledge,

and it is therefore evident that the appendedclaims should be given a broad interpretation in accordance with the step taken in the art, and we should not be restricted to any particular acid or acids in thecarrying out of our process.

Having thus disclosed our invention, we claim and desire to secure by Letters Patent: 1. The process of cleansing a well hole of colloidal mud from the walls of said wellhole, which consists in introducing an acid within said well hole to break up the mud colloids.

2. The process of cleansing a well hole of colloidal mud from the walls of said well hole, which consists in introducing an acid within said well hole to break up the mud colloids, then removing the muds.

3. The process of cleansing the walls of a well hole of colloidal mud, which consists in introdncingan acid within said well hole to break up and suspend said colloids by acid action upon said colloidal mud, then removing said mud from the well hole.

4. The process of cleansing a well hole of colloidal muds which consists in introducing an acid solution within said well hole and tmrmitting said solution to act upon the colloidal mud to break up the same and suspend the same in said acid solution.

5. The process of cleansing a well hole of colloidal mud which consists in introducing an acid solution within said well hole, permitting said solution to act upon the colloidal mud to break up the same and suspend the same in said acid solution, then removing said colloidal mud by an aqueous vehicle.

(l. The process of cleansing a well hole of colloidal mud from the walls of said well hole, which consists in introducing an acid within said well hole to chemically destroy the colloidal property of such mud.

.7. The process of cleansing a well hole of colloidal mud from the walls of said well I hole, which consists in introducing an acid within said well hole to chemically destroy the colloidal property of such mud and to put such mud in part into solution.

8. The process of cleansing a well hole of colloidal mud when metallic apparatus is therein, consisting in introducing an acid within the well hole to render the mud ca-' pable of withdrawal from the hole under liquid lift.

9. The process of cleansing a well hole of colloidal mud, which consists in introducing an acid within said well hole to render the till 

